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A delegate said Donald Trump's senior adviser told him the campaign was dropping its challenge on Colorado's results

Paul Manafort characterized the exchange as a "passing comment," not a change of position

(CNN)A Republican National Convention delegate from Colorado said Friday that Donald Trump's senior adviser told him the campaign was dropping its challenge to rival Ted Cruz's sweep of the state's delegates -- an account the campaign is disputing.

Guy Short, a national delegate from Colorado and member of the convention's rules committee, said he approached Trump's convention manager, Paul Manafort, after he gave Republican Party insiders a private briefing in Florida earlier this week and asked about Trump's threat to challenge what the billionaire has called a "rigged" system.

"Is the Trump campaign going to challenge the credentials of the Colorado delegation? And he said, 'no,'" Short, a Cruz supporter, said. According to Short, Manafort "said, 'Cooler heads have prevailed. We're moving forward. We're trying to unite the party.'"

But Manafort told CNN in an interview Saturday that Short's characterization is "not quite true." He said he told Short the campaign is investigating and would consider dropping the challenge if the facts don't support one.

"The reality is Donald Trump is very upset about the fact that voters were cut out of the process," Manafort told CNN's "Newsroom."

In an email to CNN, Manafort downplayed the exchange as a "passing comment," not a change of position.

"A final decision will be made when our investigation is finished," Manafort wrote.

Mike McAlpine, an unbound Colorado delegate who favors Cruz, said he witnessed the conversation between Short and Manafort and corroborated Short's version. Short called Manafort's description "pure fantasy."

Trump has complained bitterly that Cruz's sweep of Colorado's 34 pledged delegates at the state's convention was the result of a "rigged," "corrupt" and "crooked" system. Trump has railed against states like Colorado and Wyoming that have chosen their delegates through state conventions instead of holding a primary or caucus, arguing that people were denied the right to vote.

Republican National Committee officials have fired back against Trump's criticisms, arguing that the candidates have known the rules for months. Republicans, party officials have argued, have used the same nomination process since 1860.

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In fact, Short said Manafort's Florida briefing sounded like an attempt to mend fences with party insiders that Trump has been trashing on the campaign trail. Had Manafort told him that the Trump campaign was still considering protesting Colorado's results, "the whole tenor of his talk would have been contradicted," Short said.

Short said he also asked Manafort if Trump still believes that Cruz bought off Colorado's delegates. Short said Manafort told him that Trump did not believe that was the case in Colorado.

"There were no freebies offered to anybody," Short said. "I would have called him a liar if he had said that."